Being separated is not all that bad.
I had posted before about lens element separation, so I thought I would follow up with real life effect of this. I was fortunate enough to get a hold of another lens that has no lens separation, so I thought I would take some picture using them.
Both are Minolta Chiyoko Super Rokkor 45mm f/2.8 LTM lenses. The one on the right shows separation of the front element group by the foggy outer ring.
Lets see how usable the lens is … using my Sony NEX-6, APS-C 16Mpixel @ 400ISO.
Wide open at f/2.8 … SOOC. The sun is in front of the camera. No lens hood.
Notice that there is a drop in contrast as there is a lot of internal light reflection, and a slight drop in sharpness.
The shot with the good lens looks … good.
I took the first image and used the dehazing tool in Lightroom
Hmm, not bad … some sharpness is still obtainable in the centre … this is a 100% crop
I did take some shots with the lens stopped down to f/16 … I didn’t bother to show examples as the images appeared too similar, just take my word for it.
Soooo, if you have just outer separation you could use the lens for that slightly soft portrait imagery that many people replicate using digital post processing plugins/filters … well you can be the judge of that.